1. Field of the Invention
This invention relates to a circuit interrupter and more particularly to an interrupter of the vacuum type which includes an evacuated envelope, in which a pair of movable and stationary contact rods are arranged to open or close a circuit.
2. Description of the Prior Art
In a vacuum circuit interrupter of the prior art, a pair of contacts engaging selectively with each other are housed within an evacuated envelope composed of a proper combination of insulating and metallic members, the former being made of glass or ceramic and the latter being made of an iron-nickel or iron-nickel-cobalt alloy having a coefficient of thermal expansion which closely matches that of the glass or ceramic. However, the iron-nickel or iron-nickel-cobalt alloy is relatively expensive.